The present invention refers to a device for copying essentially transparent photographic masters onto photographic copy material, as well as a minilab for producing copies of photographic masters.
The production of copies, usually paper images, of masters, usually negative films, is carried out nowadays more or less fully automatically. The customer hands over to the retailer either an undeveloped film or already developed negatives (subsequent orders) and tells him which negative he wants copies of, how many copies and in what format he wants them. The film or the negatives are either forwarded to large development labs or are processed with what is known as a minilab or microlab at the retailer's facilities.
In large development labs as well as in minilabs, the negatives are then developed (insofar as they have not already been developed, as in the case of subsequent orders), the developed negatives are then exposed onto paper, and the exposed paper is then developed. For developing the negatives and for developing the exposed paper, wet-chemical baths are required. Whereas in large development labs, the individual system sections (wet-chemical section for the negatives, printer, wet-chemical section for the paper) are usually separate from each other, in what are referred to as minilabs they are all integrated into the minilab.
In large development labs as well as in minilabs, the wet-chemical system sections must be regularly and routinely checked in order to guarantee the quality of the copies. For this reason, the settings of the copying apparatus, i.e., the printer, must also be routinely checked on a daily basis. For these purposes, densitometers are used in the photographic industry.
For checking the wet-chemical sections, i.e., the film or paper developing baths, corresponding film chemical strips or paper chemical strips are measured. These strips have already been exposed in standardized manner at the respective film or paper manufacturer's facilities and are developed at regular intervals in the respective film or paper developing baths. The developed film or paper strips are photometrically evaluated with a densitometer and compared with the target specifications of the respective manufacturer. Depending on the results produced, the developing baths are refreshed or regenerated, renewed or maintained unchanged.
To check the settings of the photographic printer, one or more standard negatives are exposed on photographic paper and developed with a ready-to-use chemical product. The developed images are photometrically evaluated with the densitometer and compared with target standards. Depending on the values determined, the basic settings of the printer can be varied.
Densitometers suitable for such purposes are described, for example, in U.S. Pat. No. 5,118,113 and are also known in the form of apparatuses of the 880 series from the X-Rite company. These densitometers are equipped for reflection operation for opaque test strips as well as for transmission operation for transparent test strips, and they accordingly have a stationary reflection measuring system or a stationary transmission measuring system, respectively. Filters also arranged stationary inside the apparatus make it possible to determine the corresponding reflection or transmission densities of the test strip for different wavelengths, preferably for the three basic colors red, green and blue. A motor-driven conveyance device conveys the test strip through the apparatus.
With the help of such a densitometer, it is of course possible to measure the test strips, exposed in standardized manner by the manufacturer, after they have been developed in the wet-chemical baths and, using the measurement results, to verify whether the baths need to be refreshed, regenerated or renewed or whether they can be maintained unchanged. With the help of such an apparatus, it is also possible to check the basic settings of the printer in which the standard images are measured. Depending on the measurement results, the basic settings of the printer can then be varied.
Nevertheless, the described densitometer is an autonomous device which, although it can be linked to the printer, remains an independent apparatus. The result of this is that the operating personnel has to operate an additional apparatus. It has therefore already been proposed to integrate the densitometer into the printer. This does not involve any substantial problems for large development labs, since such large development labs are not primarily designed to save space. On the other hand, this solution represents a considerable disadvantage for minilabs since, in addition to the printer, the wet-chemical sections are also closely fitted into these minilabs, and the need for space in minilabs plays a substantial role in times of increasing space shortage.